U.S. patent number 6,955,162 [Application Number 10/687,163] was granted by the patent office on 2005-10-18 for internal combustion engine with pressure boosted exhaust gas recirculation.
This patent grant is currently assigned to International Truck Intellectual Property Company, LLC. Invention is credited to Anthony J. Cook, Gerald L. Larson.
United States Patent |
6,955,162 |
Larson , et al. |
October 18, 2005 |
Internal combustion engine with pressure boosted exhaust gas
recirculation
Abstract
An exhaust gas recirculating system for a turbocharged diesel
engine utilizes an electrically driven compression pump to boost
exhaust gas pressure before return to the engine induction system.
Exhaust gas is drawn from the exhaust system or stack some distance
removed and downstream from the outlet from the exhaust turbine,
compressed to overcome the intake manifold boost pressure, and
returned to the intake system along an extended pipe to cool the
gas. The compressor is energized from the vehicle battery during
periods of demand for peak pressure demand on the engine thereby
recycling recaptured energy from the battery to boost engine
output. Exhaust turbine performance during periods of peak loading
is also improved.
Inventors: |
Larson; Gerald L. (Fort Wayne,
IN), Cook; Anthony J. (Fort Wayne, IN) |
Assignee: |
International Truck Intellectual
Property Company, LLC (Warrenville, IL)
|
Family
ID: |
34520881 |
Appl.
No.: |
10/687,163 |
Filed: |
October 16, 2003 |
Current U.S.
Class: |
123/568.11;
123/568.21; 60/278; 60/605.2 |
Current CPC
Class: |
F02D
41/0065 (20130101); F02M 26/47 (20160201); F02M
26/34 (20160201); F02M 26/07 (20160201); F02D
23/02 (20130101); Y02T 10/12 (20130101); Y02T
10/144 (20130101); F02M 26/27 (20160201); F02B
3/06 (20130101); Y02T 10/40 (20130101); F02M
26/15 (20160201); F02B 29/0406 (20130101); Y02T
10/47 (20130101); F02D 41/12 (20130101) |
Current International
Class: |
F02D
21/00 (20060101); F02D 23/02 (20060101); F02D
23/00 (20060101); F02D 21/08 (20060101); F02M
25/07 (20060101); F02D 41/12 (20060101); F02B
29/04 (20060101); F02B 3/00 (20060101); F02B
3/06 (20060101); F02B 29/00 (20060101); F02M
025/07 (); F02B 033/44 () |
Field of
Search: |
;123/568.11,568.12,568.21 ;60/278,279,605.2 ;477/2,3,7
;180/65.1,65.3,65.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolfe, Jr.; Willis R.
Attorney, Agent or Firm: Calfa; Jeffrey P. Sullivan; Dennis
Kelly Lukasik; Susan L.
Claims
What is claimed is:
1. An internal combustion engine system comprising: an internal
combustion engine; an air intake system to the internal combustion
engine; an exhaust system from the internal combustion engine; an
exhaust gas recirculating line having an inlet from the exhaust
system and an outlet into the air intake system; a compressor
system in the exhaust gas recirculating line for drawing exhaust
gas from the exhaust system and boosting exhaust gas pressure for
delivery to the air intake system; an engine controller and engine
sensor package for detecting when the internal combustion engine is
under negative and positive loads; a transducer coupled to receive
mechanical energy from the internal combustion engine; energy
storage means for receiving energy output by the transducer and
storing the energy; means responsive to detection of a negative
load on the internal combustion engine for coupling the energy
output of the transducer to the energy storage means for storage as
potential energy; and means responsive to detection of a positive
load on the internal combustion engine for tapping the energy
storage means for energy for driving the compressor system in the
exhaust gas recirculating line.
2. An internal combustion engine system as set forth in claim 1,
further comprising: the air intake system including a charge air
boost system for raising the pressure of air in the air intake
system; the exhaust system including an exhaust turbine coupled to
drive the charge air boost system, the exhaust turbine further
having an inlet for receiving exhaust gas from the engine and an
outlet into an exhaust pipe for discharge to the environment; and
the exhaust gas recirculating line having its inlet from the
exhaust system connected to the exhaust pipe downstream from the
outlet from the exhaust turbine.
3. An internal combustion engine system as set forth in claim 2,
further comprising: the exhaust gas recirculating line being
sufficiently long to provide substantial exhaust gas cooling prior
to introduction of the exhaust gas to the air intake system.
4. An internal combustion engine system as set forth in claim 3,
further comprising: the air intake system having an intercooler
downstream from the charge air boost system and an intake manifold
between the intercooler and the engine; and the outlet from the
exhaust gas recirculating line into the air intake system is
downstream from the intercooler and ahead of the air intake
manifold.
5. An internal combustion engine system as set forth in claim 4,
further comprising: the compressor system further including, an
electrically driven compressor; and a metering valve coupling the
outlet of the compressor to the air intake system; the transducer
being an electrical generator; and the energy storage means being a
battery.
6. An internal combustion engine system as set forth in claim 4,
further comprising: the compressor system further including, a
variable output electrically driven compressor; and a fixed
diameter return orifice between the compressor and the outlet to
the air intake system; the transducer being an electrical
generator; and the energy storage means being a battery.
7. An internal combustion engine system as set forth in claim 6,
wherein the internal combustion engine is a compression ignition
engine.
8. An internal combustion engine assembly comprising: an internal
combustion engine; an intake manifold to the internal combustion
engine; an exhaust manifold from the internal combustion engine; a
turbocharger having a combustion air intake, an exhaust gas intake
from the exhaust manifold, an exhaust gas outlet and a compressed
intake air outlet coupled to the intake manifold; an exhaust gas
recirculating line fluidically coupled to the exhaust gas outlet of
the turbocharger and further coupled to the intake manifold to
return exhaust gas to the intake manifold from the exhaust gas
outlet; a compressor in the exhaust gas recirculating line for
pressurizing the exhaust gas; a battery; a charging system coupled
to the internal combustion engine assembly for energization and
electrically coupled for returning charge to the battery; and the
compressor being electrically energized from the battery responsive
to transient conditions on the internal combustion engine.
9. An internal combustion engine assembly as set forth in claim 8,
further comprising: an extended exhaust pipe coupling the exhaust
gas outlet from the turbocharger to the exhaust gas recirculating
line.
10. An internal combustion engine assembly as set forth in claim 9,
further comprising: the compressor having a controllable
output.
11. An internal combustion engine assembly as set forth in claim 9,
further comprising: a metering valve coupling the compressor to the
intake manifold.
12. An internal combustion engine assembly as set forth in claim
11, further comprising: an engine controller for energizing the
electrically driven compressor and coupled to the metering valve
for the control thereof.
13. A motor vehicle comprising: an internal combustion engine
having an intake manifold and an exhaust manifold; an exhaust
turbine coupled to receive exhaust gas from the exhaust manifold; a
supercharger connected to be driven by the exhaust turbine and
coupled to boost charge air into the intake manifold; an exhaust
pipe connected to and extending from the exhaust turbine to carry
exhaust gas from the exhaust turbine; an exhaust gas recirculating
conduit including an exhaust gas compressor disposed in the exhaust
gas recirculating conduit, the exhaust gas recirculating conduit
being connected to the exhaust pipe to allow the exhaust gas
compressor to draw exhaust gas from the exhaust pipe and to boost
the pressure of the exhaust gas for delivery into the intake
manifold; an electrical supply system powered by the internal
combustion engine and including an electrical power storage device;
the compressor being electrically driven; and means responsive to
engine load for alternatingly energizing the compressor from the
electrical power storage device and charging the electrical power
storage device.
14. A motor vehicle as set forth in claim 13, further comprising: A
NO.sub.x emission reducing system in the exhaust pipe; and the
point of connection between the exhaust gas recirculating conduit
and the exhaust pipe being downstream from the NO.sub.x emission
reducing system.
15. A motor vehicle as set forth in claim 14, further comprising:
an intercooler coupling the charge air from the supercharger to the
intake manifold; and the exhaust gas recirculating conduit being
coupled to deliver boosted exhaust gas to the intake manifold
downstream from the intercooler.
Description
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to exhaust gas recirculating systems for
internal combustion engines and more particularly to an exhaust gas
recirculating system for a turbocharged diesel engine.
2. Description of the Problem
Turbocharging is a well known method for increasing the efficiency
and boosting the peak power output of an internal combustion
engine. An exhaust energy recovery turbine is positioned in the
exhaust stream from the engine and uses energy from the exhaust gas
to drive a supercharger disposed in the engine's air intake system.
The supercharger boosts the density of air delivered to the
engine's intake manifold. The increased air density allows
additional fuel to be introduced to the cylinders and combusted,
increasing engine output. Turbocharging, while used occasionally
with spark ignition engines, is more commonly found in compression
ignition engines, i.e. diesel engines.
Complicating the application of turbocharging to diesel engines is
the need to meet government emission standards, particularly those
relating to NO.sub.x emissions. One way in which emissions are
reduced is through the use of exhaust gas recirculating systems
(EGR) in which exhaust gas is returned to the air intake system.
The air intake system for a supercharged diesel engine includes the
compressor pump and, usually, an intercooler between the
supercharger and the engine's intake manifold. Exhaust gas can be
returned ahead of the supercharger, into the intercooler, or
directly into the intake manifold. Exhaust gas may be drawn from
the exhaust manifold ahead of the energy recovery turbine, or from
some point further down the exhaust system. The most common
arrangement is to draw exhaust gas directly from the exhaust
manifold and to deliver the gas to intake manifold, usually passing
the exhaust gas through an intercooler in the EGR line. See, by way
of example, U.S. Pat. No. 6,470,864 to Kim et al., U.S. Pat. No.
6,247,311 to Itoyama et al., and U.S. Pat. No. 6,412,278 to
Matthews. It is usually considered undesirable to return the
exhaust gas to the intake system ahead of the supercharger or the
intake intercooler due to the potential of corrosion the exhaust
gas poses for these components. The exhaust gas is considerably
hotter than ambient air and this reduces the flow mass through the
supercharger compressor and reduces the power output of the engine.
While Kim et al. and Itoyama et al. provided no pressure boost for
the exhaust gas, Matthews stated that the exhaust gas from the
exhaust manifold may not have sufficient pressure to allow smooth
delivery of the gas into the intake manifold due to pressures in
the intake manifold. Matthews provided a hydraulically driven pump
in the exhaust gas recirculating line to assure sufficient exhaust
gas pressure for delivery to the intake manifold.
Many prior art EGR systems have the disadvantages of introducing an
extremely high temperature gas to the engine induction system and
of diverting exhaust air flow from the exhaust turbine, reducing
the turbine's effectiveness. While all position an intercooler in
the EGR line to reduce exhaust gas temperature, these systems still
release a great deal of heat into a vehicle's engine compartment,
promoting engine overheating. In addition, the need for an
intercooler in the EGR line adds substantial expense to the
systems.
Cook, U.S. Pat. No. 6,470,866 proposed diverting exhaust gas from
the exhaust pipe downstream from the exhaust turbine. This was
achieved by restricting flow through the exhaust pipe to boost the
pressure of the gas. However, this arrangement increases exhaust
system back pressure which again reduces exhaust turbine
performance. The prior art proposals considered have all had the
disadvantage of reducing peak engine output.
SUMMARY OF THE INVENTION
According to the invention there is provided an internal combustion
engine having an air intake system and an exhaust system. Air drawn
into the air intake system is boosted by an exhaust gas driven
supercharger. An intercooler is usually disposed between the air
outlet from the supercharger and an engine intake manifold to
increase charge air density. Exhaust gas is drawn from the exhaust
system downstream from the exhaust turbine and compressed for
return to the air intake system. Pressurized exhaust gas is
introduced to the intake system above the intake manifold and after
the intake system intercooler. An electric compressor motor drives
the recirculated exhaust gas compressor. Power for the compressor
motor is supplied from the vehicle electrical system and during
periods of highest pressure demand on the engine, almost
exclusively from the vehicle's battery plant. When peak engine
output is required the compressor avoids reduction in the pressure
drop across the exhaust turbine, improving vehicle performance.
Battery recharging is directed toward periods when engine load is
negative allowing the exhaust gas recirculating system to cooperate
with the battery charging system as a vehicle kinetic energy
recovery system. Exhaust gas is drawn from the exhaust pipe well
outside the engine compartment, after particulate removal (if used)
and NO.sub.x reduction, which reduces the temperature of the
exhaust gas and the pollution levels thereof without the need for a
supplemental EGR line intercooler. This arrangement helps transport
waste heat from the engine compartment and reduces the
corrosiveness of the recirculated exhaust gas.
Additional effects, features and advantages will be apparent in the
written description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features believed characteristic of the invention are set
forth in the appended claims. The invention itself however, as well
as a preferred mode of use, further objects and advantages thereof,
will best be understood by reference to the following detailed
description of an illustrative embodiment when read in conjunction
with the accompanying drawings, wherein:
FIG. 1 is a plan view of a vehicle chassis.
FIG. 2 is a schematic diagram showing a turbocharged engine
assembly with boosted exhaust gas recirculating.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the figures and in particular to FIG. 1 a vehicle
chassis 10 is illustrated. Vehicle chassis 10 includes a frame 11
which supports an internal combustion engine 12 and its drive train
13. Engine 12 has an air intake or induction system 14 into which
air is drawn from the ambient environment and compressed for
delivery to the engine's cylinders. A high pressure stage exhaust
system 16 from engine 12 includes an exhaust manifold and at least
a first stage exhaust turbine. The first stage exhaust turbine is
mechanically coupled to a compressor/supercharger in the air intake
system 14 to compress air for the air intake system. Engine 12 and
high pressure stage exhaust system 16 are located toward the front
of vehicle chassis 10 in an engine compartment 15. Engine 12 is
preferably an ignition compression engine.
Extending toward the back of vehicle chassis 10 from high pressure
stage exhaust system 16 is a low pressure exhaust system 19 which
is illustrated as including an exhaust pipe 20, a particulate trap
22, an SCR catalytic converter or NO.sub.x adsorber 24 and a
muffler 26. Typically an exhaust system will include either the
particulate trap 22, or the muffler 26, but not both. An exhaust
gas recirculating (EGR) line 21 is connected via sampling line 18
to exhaust pipe 20 at a point downstream from NO.sub.x adsorber 24
and between the adsorber and muffler 26 (if present). Preferably,
the point of connection is as far removed from the engine
compartment 15 as feasible to allow for cooling of the exhaust gas
in the exhaust pipe 20 and EGR recirculating line 21. Exhaust gas
is drawn into EGR sampling line 18 by an electrically driven
compressor pump 28 located in return line 21. Compressor 28 is
likewise located at a point relatively removed from engine
compartment 15. EGR return line 21 extends between compressor 28
and air intake system 14 and is made relatively long to allow
cooling of the compressed exhaust gas before introduction to the
air intake system. Preferably, EGR return line 21 delivers exhaust
gas to the engine intake manifold 34. Exhaust gas can be returned
to other points in the intake system, such as upstream from
supercharger 30 (as shown in phantom in FIG. 2) and still provide
energy recycling and improved efficiency as described below, but
such an arrangement is not considered desirable.
Referring now to FIG. 2, a preferred embodiment of an engine
assembly 100 incorporating a diesel engine 12, turbocharging and
exhaust gas recirculating is shown. Engine assembly 100 draws air
from the ambient environment (typically through an air filtration
system which is not shown) into a supercharger 30. Compressed air
is discharged from supercharger 30 to an intercooler 32 to reduce
the temperature of the gas and thereby increase its density for
introduction to an intake manifold 34 for diesel engine 12. Fuel
from fuel injectors 48 is mixed in the cylinders of engine 12 with
air drawn from intake manifold 34. Compression ignition of the
mixture occurs in the cylinders and exhaust gas is generated. The
exhaust gases pass to an exhaust manifold 36 in the high pressure
stage of the exhaust system. The exhaust gases are under
considerable pressure and are used to drive an exhaust turbine 38
which is mechanically coupled to drive supercharger 30. Exhaust gas
is typically discharged from the exhaust turbine 38 to an exhaust
pipe 20, although in some vehicles incorporating turbocompounding,
a second stage exhaust turbine (not shown) may be present which is
mechanically coupled to an engine drive shaft (not shown). Exhaust
gas temperature falls on passage through the exhaust turbine as
work is extracted from the gas.
From the exhaust turbine 38 exhaust gas passes down exhaust pipe 20
through a particulate trap 22 (if used) and through an NO.sub.x
adsorber or SCR catalytic converter 24. After discharge from SCR
catalytic converter 24 into exhaust pipe 20 the exhaust gas passes
to a muffler 26 (when no particulate trap is used) and finally out
of the exhaust system into the environment. Exhaust gas for
recirculating is drawn from exhaust pipe 20 downstream from SCR
catalytic converter 24 into an EGR sampling line 18 by a
electrically driven compressor pump 28 in EGR return line 21. The
exhaust gas is pressurized sufficiently by compressor 28 for
delivery to intake manifold 34, overcoming the pressurized intake
air in the intake manifold. The discharge of pressurized exhaust
gas from EGR return line 21 into intake manifold 34 is usually
controlled by an exhaust gas recirculating metering valve 44
positioned between the discharge of compressor 28 and the intake
manifold. Metering valve 44 may be replaced by a fixed diameter
orifice if the output of compressor 28 is subject to variable
control by engine controller 46. Since exhaust gas is drawn from
exhaust pipe 20 by a pipe the back pressure in the exhaust pipe is
reduced and the operation of exhaust turbine 38 is not negatively
affected, and may be improved. By tapping energy from battery 52 to
drive motor 42 for compressor 28 the output of engine 12 is
increased during periods when peak output is demanded of the
engine. In addition, exhaust gas is introduced to intake manifold
34 with no turbocharger induced lag thereby improving transient
response.
Engine controller 46 is programmed to provide control over exhaust
gas recirculating responsive to engine operating conditions.
Exhaust gas pressure is set at a level to obtain a fixed ratio of
the recirculated exhaust gas pressure to the pressure of the air in
the air intake manifold 34. Pressure sensor 40 in EGR return line
21 and a intake manifold pressure sensor included in engine sensor
package 49 provide the required pressure readings. Electrically
driven compressor 28 is driven by electric motor 42 which is
mechanically coupled to compressor 28. Compressor 28 itself is
preferably an electrically operated free piston device or a scroll
compressor. These devices exhibit high efficiency without the need
for lubrication, which prevents the possibility of passing
lubricating oil from the compressor to the intake manifold 34.
Engine controller 46 controls energization of electric motor 42 and
may control the speed or output of the motor. If used, the position
of exhaust gas recirculating metering valve 44 is also determined
by control signals provided by engine controller 46. Where valve 44
has been replaced by fixed diameter orifices, the speed of motor 42
is varied by engine controller 46 to obtain the desired exhaust gas
pressure. In either case EGR pressure is adjusted in response to
intake manifold pressure to obtain a fixed pressure ratio. Engine
controller receives inputs from a power demand input source and
from a number of engine sensors 49, including cam position sensing,
engine oil operating temperature, coolant temperature, propeller
shaft speed, intake manifold pressure, exhaust manifold pressure,
etc., to effect the desired control. The engine controller 46 also
controls fuel injection timing and quantity, and can, accordingly,
estimate engine load and determine periods of peak system pressure
or output demand. Energization of electric motor 42 exclusively
from battery 52 occurs during transient conditions, e.g. vehicle
launch, which are characterized by low engine RPMs and high demands
for pressure.
A vehicle electrical system conventionally includes a battery
charging system 50 and a battery 52. The battery charging system 50
typically includes an alternator which is belt driven from engine
12. Motor 42 is energized from the vehicle electrical system,
either from the battery charging system 50 or by discharge from
battery 52 should the output of the battery charging system 50 be
diverted by the engine controller 46. Diversion may be by means of
a switch 58, which shifts the power source to battery 52 during
periods of high pressure demand on engine 12. Engine controller 46
monitors the charge state of battery 52 using appropriate
instrumentation, such as a voltmeter 54. Engine controller 46
effects energy recapture by emphasizing charging of battery 52
during periods when the engine 12 is under a negative load. In
effect the charging system 50 is then used as a brake. Such
negative loading occurs when the vehicle is going downhill or
stopping. By use of the term "emphasizing" it is meant that a
programmable device, such as the engine controller 46 or another on
board computer tends to limit battery charging to periods of
negative load by only allowing charging during those periods or
when the battery exhibits an undesirably low state of charge. The
invention provides for tapping this recovered energy during vehicle
transient or launch conditions when engine RPMs are low and the
call for all pressures is higher. On these occasions energy is
drawn from battery 52.
Exhaust gas recirculating with the present invention avoids EGR
heat release in the vehicle engine compartment. Improved engine
output under high demand conditions is met while maintaining the
pressure drop across the exhaust turbine under peak load
conditions. In some applications as much as 15 HP can be recovered
during peak load conditions on engine 12. Exhaust gases are
recovered for recirculating after treatment, making the gases both
cleaner and cooler than in prior art EGR systems. Energy recovered
and stored as electrical power is recycled to drive the EGR
compression pump during periods of high pressure demand on the
engine, e.g. during vehicle launch from a standing start. Engine
controller 46 is otherwise programmed to implement with
conventional exhaust gas recirculating control algorithms
minimizing the modifications required to implement the
invention.
While the invention is shown in only one of its forms, it is not
thus limited but is susceptible to various changes and
modifications without departing from the spirit and scope of the
invention.
* * * * *